Method of pest control



These oils may derive either from cracking of fact that aromatic hydrocarbons possess highest Patented 6,1945

METHOD on nest con'mol.

Theodore G. Roehner. Malverne, N. assignor to Socony-Vacuu'm Oil Company, Incorporated, New York, N. Y.. a corporation of New York No Drawing. Application April 2, mi, Serial No. 386,431

7 Claims. (01. 187-30) This invention has to do with methods of pest I control, and particularly with methodsfor the control and elimination of mosquitoes and similar pests having water dwelling larvae. The most generally used method of control for such pests has been the coating of the surface of stagnant water bodies with oil films leading to the killing of. the insect while in the larval stage. This water-dwelling life phases, such as larvae and pupae of the pests in question must frequently come to the surface to breathe air. The larvae coming into contact with the oil film on the surface of the water body, are killed, apparently two functions of the oil being responsible for this effect. The first is the interference of the oil with the breathing and other bodily functions of the larvae that inhale the air through spiracles, numerous air pores on their bodies. The second I is the toxicity possessed by the oil.

While the above known mosquito control I method is quite sound, it is efiective only when a permanent and continuous oil film is maintained on the surface of water bodies. However, the currents, and especially the slightest wind, tend to drive the oil to the edges of the water body and around the stem of emerging plants and the like. Thus the oil soon becomes entirely unavailable for its intended purpose.

In order to overcome this handicap, repeated treatments of the surface ,of pools and puddles have been made during theseason, and such repeated sprayings, even with the cheapest of 1 oils, are frequentlyprohibitive in cost. Second,

' due to this cost feature, only the cheapest grades of oil could be used and these are of low toxicity and unsuitable viscosity.

I have invented a process of pest control, par- 4 vticularly mosquito control, which is based on an They are all lighter than water and float on its surface. There are, however, hydrocarbon oil: which possess specific gravity higher than water.

petroleum, or from coal tar, or from any other process which yields cyclic hydrocarbons.

The selection of such products is especially beneficial for pest control because of the known viscosity.

' method is based on the known fact that the toxicity insects among all other known hydrocarbons.

Another important characteristic which determines the suitability of an oil for mosquito or pest control, particularly water dwelling larvae, is the In fact, while heavy asphaltic fluxes or heavy coal tarb'ottoms would meet the requirements 'as to specific gravity and toxicity, they do not lend themselves for atomizing and economical application. What I propose is the distribution below the surface and upon the bottom of such water bodies of an oily toxic material in films or globules or otherwise, and this can be done eco nornically only withoils of certain viscosity.

The following will exemplify my invention. A cut from the recycle stock produced by catalytic vapor phase cracking of gas oil from a Coastal crude (naphthenic crude) possesses the following characteristics.

It will be noted that this oil has an exceptionally low A. P. I. gravity (or in other words, a high specific gravity for an oil of such low viscosity). It indicates a highly cyclic nature of the hydrocarbons predominant in this oil. Actual experi-' ments conducted by a laboratory specializingin mosquito control have shown its high toxic eilect to several'species or mosquito larvae. When.addltional larvae were placed in the test pool several days after the application of the oil, they were killed as quickly as on the first day of application.

' This should be expected because the toxic components of the oil are not chemically reactive with Obviously the oily materials in question may be- I applied either as a spray of oil, or in the form of an emulsion or dispersion, or as an oil con} taining an emulsifier which becomesactive upon contact with water. In-many cases these latter methods will secure more efl'ective distribution andmoreeconomiealuse.Asanexampleol' such methods, a small-amount or an emulsifier suchasanalkalimetalsaltoiamineraloilsulionate, or a soap of whale oil may be added to the oil and the mixture may be applied as such, or may be dispersed in water prior to application. Also the oil may be utilized as the vehicle for added toxic materials such as cresylic acid which may be dissolved in the oil, or oil-insoluble insecticides which may be dispersed in the oil itself or dispersed in the oil emulsions when uch are used. r

Also it has been observed that when lower specific gravity hydrocarbon oils are added, there appears to be material separation upon application, embracing both the forming of a surface film after the older method, and the distribution oi other and significant portions of the oil'below the surface and upon the bottom of the water body.

All these modifications I consider as being within the scope of my invention, subiect only to the limitations set forth in the claims append- .ed hereto.

While the above .011 set forth in Table I is an example of a product suitable for the novel pest control method claimed in' this application, hydrocarbon oils of different origins such as extracted, distilled or obtained by the decomposition of bituminous material, coal, iig nite, petroleum, etc. are perfectly suitable for the purpose.

Table II sets forth the range of specifications of oils possessing the desirable properties for bottom application in water bodies.

Gravity .3 A. P. 1-- Below 10 Viscosity 100 F. Say. Univ. From 30" to 400" Pour point F Below 50 Viscosity-gravity-constant 0.870 minimum By way of comparison with oils of usual used heretofore {or mosquito control, the following Table III shows what the gravity and viscositles or usually used oils would be for the viscosity range specified.

Viscosity-gravity-constant Below 0.890

Thusitmaybenotedthattheoilshereinprm posed are quite diflerent from oils. formerly used inthat they possess a specific gravity higher than water coupled with a relatively low viscosity.

All oils formerly used were lighter than water.

The novel oils here disclosed may be defined as thoseoilshaving a specific gravity greater than 1.0 (below 10 A. P. I.) and having a minimum viscosity gravity constant of 0.870. This viscosity gravity constant, as is well known in the oil industry is a measure of the relative amounts of straight chain or cyclic hydrocarbons present, and in the range specified indicates an oil quite highly aromatic or cyclic in character.

1. That method of controlling insects having a water-dwelling lite phase comprising applying to the water bodies wherein they may develop a hydrocarbon oil of highly cyclic nature having a specific gravity of at least 1.0 based on water.

2. That method of controlling insects having a water-dwelling life phase comprising applying to and within the water bodies wherein they may develop a hydrocarbon oil of .highly cyclic nature having a specific gravity of at least 1.0 based on water and a viscosity gravity constant of at least 0.870.

3. That method of controlling insects having a water-dwelling lite phase comprising applying to and within the water bodies wherein they may develop an oieaginous composition characterized by the presence of a substantial p p rtion of a hydrocarbon oil of highly cyclic nature having a specific gravity of at least 1.0 based on water.

4. That method of controlling insects havin a water-dwelling lite phase comprising applying to the water bodies whegeinthey may develop an oleaginous composition comprising a hydrocarbonoil of highly cyclic character having a specific gravity of at least 1.0 based on water and in addition thereto an added toxic material. 5. That method of controlling insects having a water-dwelling life phase comprising applying to and within the water bodies wherein they may develop an oleaginous composition comprising a hydrocarbon oil of highly cyclic character having a specific gravity or at least 1.0 based on water and in addition thereto a material capable of promoting the dispersion of the oil in water.

8. That method of controlling insects having,

a water-dwelling lire phase comprising applying .to the water bodies wherein they may develop an oleaginous composition comprising a hydrocarbon oil of highly cyclic character having a specific gravity of at least 1.0 based on water and in addition thereto an emulsifier and an added toxic material.

' 7. That method of controlling insects having a water-dwelling lite phase comprising applying toandwithinthe waterbodieswhereintheymay develop'an oleaginous composition comprising an oil-in-water emulsion of a hydrocarbon oil of highly cyclic character having aspecific gravity of atleast 1.0 based mum.

THEODORB GIRO 

